[Xen-devel] Intercept system call trap on Xen,

[Hui Kang <hkang@xxxxxxxxxxxxxxxxx>]

Hi, 

I have a question regarding intercepting the system call from a guest kernel on hypervisor. I am using xen-4.0.1 with a PV-guest. 

To disable the fast system call which bypasses the hypervisor, I first comment out this lines in the file

Xen/arch/x86/traps.c

      If (cur.vector == 0x80)

       {

    /* init_int80_direct_trap(curr); */

}

To verify this, when I boot the kernel, I add printk and see that init_int80_direct_trap is not executed. 

Then in the function in the same file as above, do_guest_trap, I add a printk to trap the system call from guest kernel

Static void do_guest_trap…

{

If (trapnr == 0x80)

printk("System call from guest");

}

However, when I run some program in the guest kernel to issue some system call, the hypervisor does not print out the message. Can anyone help on this? Thanks. 

- Hui

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